Reflex reflective sheeting

ABSTRACT

New and improved structures in reflective sheeting are provided which may be produced automatically and continuously of a single material in substantially long lengths and areas larger than heretofore possible. In one form, the material of which the reflective sheeting is made comprises a flexible transparent polymer which has one or more surfaces of which sheeting has been embossed in a manner to reflect incident light striking the sheet back to the vicinity of the source.

United States Patent 1191 Lemelson Feb. 13, 1973 1 1 REFLEX REFLECTIVESHEETING 2,270,944 5 1939 Frick .101 I167 [76] Inventor: Jerome H.Lemekon, 85 Rector 236048O (W944 Dickson "35O/l02 S M h J 088402,167,149 7/1939 Grote ..40/135 tree, ewe 3,155,764 11/1964 Gill,Jr..... ....l61/4 x 22 Filed; June 24, 1970 2,128,390 8/1938 Zerilli..350/106 2,882,413 4/1959 Vingerhoets -,117/35 1 pp 56,047 1,786,95812/1930 Oestnaes ..350/103 2,875,087 2/1959 Crandon ..117/35 X RelatedApplcamn Data 1,691,708 11 /1923 EglCSOfl ..161/4 x [63] Continuation ofSer. No. 744,911, July 15, 1968,

abandoned, which is a continuationdn-part of Ser. FOREIGN PATENTS ORAPPLICATIONS N9 439,654, SePI- 965, 3,396,637 1020 520 11 1952 France..350/109 which is a continuationin-part of Ser. No. 360,954, June 11953 322O87L Primary ExaminerDaniel .l. Fritsch 52 US. (:1. ..16l/2,94/15, 117/35, Amway-Fred Phllpm,

161/131, 350/102, 350/288 [571 ABSTRACT [51 1 Int. Cl. New and improvedStructures in reflective heeting are Field of S98"!!! 130, providedwhich may be produced automatically and 117/35 R, 35 S, 35 V, 106, 107,continuously of a single material in substantially long 106, 109, 288lengths and areas larger than heretofore possible. In one form, thematerial of which the reflective sheeting References Clted is madecomprises a flexible transparent polymer UNITED STATES PATENTS which hasone or more surfaces of which sheeting has been embossed 1n a manner toreflect 1nc1dent light 2,481,757 9/1949 Jungerson ..350/103 striking thesheet back to the vicinity of the source. 2,676,518 4/1954 Rupert..350/103 2,501,563 3/1950 Colbert et a1 ..1 17/107 4 Claims, 9 DrawingFigures G ll -ll-vll- "2:" 2w "w" PATENTLU FEB 1 2197s INVENTOR, JeromeH.Lemelson REFLEX REFLECTIVE SHEETING RELATED APPLICATIONS This is acontinuation of copending application Ser.

No. 744,911, filed July 15, 1968, now abandoned,

SUMMARY This invention relates to new and improved reflex reflectingsheet materials capable of reflecting light directed thereagainst backto the source of said light. Heretofore, reflex reflective sheeting hascomprised a substrate containing a multitude of small glass sphericalbeads embedded in a surface strata thereof. Such sheeting has beenrelatively costly to produce due to the complex manufacturing techniquesinvolved in precisely forming glass spheres and properly providing saidspheres secured to the substrate to effectively reflex reflect light.While such sheet has served useful purposes, its reflective efficiencyis substantially less than the maximum attainable of a planar reflectordue to light scattering and absorption in the beads, binder andreflective material disposed in said binder.

Accordingly it is a primary object of this invention to provide a newand improved structure in a retroreflecting device provided in sheetfrom and capable of being produced in substantially larger areas thanconventional molded retro-reflectors thereby greatly increasing theversatility and applications of the reflector.

Another object is to provide an improved reflex reflecting sheetstructure which is substantially simpler in construction thanconventional reflex reflecting sheet material employing glass beads.

Another object is to provide a reflex reflecting material in sheet formwhich may be made continuously by merely properly embossing a sheet oftransparent plastic.

Another object is to provide a retro-reflecting device which is flexibleand may be made to conform to the shape of a base or substrate on whichit is mounted thereby increasing the versatility and improving theoperation of the device.

Another object is to provide a reflex reflecting device in the form of asheet having substantially greater reflecting efficiency thanconventional reflex reflecting sheeting made in part of glass beads.

Another object is to provide an improved structure in a retro-reflectingmaterial having a plurality of corner reflecting cavities formed byembossing a surface of a sheet and providing the corner reflectingsurfaces highly reflective.

Another object is to provide improved structures in reflex orretro-reflecting materials having corner reflecting surface formationswhich are metallized, thereby reducing the need to provide highlypolished reflecting surfaces.

Another object is to provide an improvedmethod and apparatus forcontinuously producing reflex reflecting sheet material automatically inareas large enough to be used as complete highway signs.

With the above and such other objects as may hereinafter more fullyappear, the invention consists of the novel constructions, combinationsand arrangements of parts which will hereinafter be more fully describedand illustrated in the accompanying drawings, wherein are shownembodiments of the invention but it is to understood that changes,variations and modifications may be resorted to which fall within thescope of the invention as claimed.

In the drawings:

FIG. 1 is a face view of a fragment of one form of retro-reflectingsheet material made in accordance with the teachings of the instantinvention;

FIG. 2 is a side view in cross section of the material of FIG. 1;

FIG. 3 is a face view of a fragment of another form of retro-reflectivesheet material also made in accordance with the teachings of theinvention;

FIG. 4 is a cross sectioned side view of FIG. 3;

FIG. 5 is a cross sectioned side view of a modified form of theinvention;

FIG. 6 is a side cross sectional view of a portion of a reflexreflecting sheet material fabricated of two embossed sheets laminatedtogether to provide a plurality of cavities within the lamination havingwall formations adapted to reflex reflect light directed against one ofthe major surfaces of the sheet;

FIG. 7 is a plan view of one form of the sheet of FIG. 6 shown as afragment thereof;

FIG. 8 is a plan view of a fragment of another form of the sheet of FIG.6 and FIG. 9 is an end view in cross section of the sheet materialsdefined in FIG. 1 to 8 applied to a curved base or substrate andconforming to the surface thereof to provide a new type of reflectingdevice.

There is shown in FIGS. 1 and 2 a structure 10 in a reflecting materialformed of a single sheet 11 of transparent plastic which sheet is soshaped and finished as to be capable of reflex or retro reflecting lightbeamed against either or both its major surfaces back in the directionof the source of said light with little loss in intensity and over asubstantial angle of incidence or incliniation of the incident light tosaid major surface. Embossed in one surface 12 of the sheet 11 are amultitude of closely spaced indentations or cavities 13 having, in FIGS.1 and 2, pyramidal shaped walls defined by notations 15,16,17 and 18which define one of said cavities. The surfaces of the cavity walls 1518are highly reflective derived either as the result of employing anembossing roll with highly polished embossing or forming surfaces on theprotrusions of said roll which form the cavities 13 in the sheet 11 orby depositing a thin, highly reflective film 19 such as a metallizedcoating of metal such as aluminum applied continuously to the surface ofthe sheet 11 containing the cavities 13 as said sheet is fed from theembossing means. Notation 19' refers to a thin film of clear plasticcoating the metallized film l9 deposited on the surfaces 15 to 18 ofeach cavity 13.

Light beamed against the surface 12a of the sheet 11 over a range ofincident angles equivalent to at least or 45 either side of the normalto the surface 12a will be reflex reflected or retro-directed back inthe direction of the incident light after reflecting off a plurality ofthe surfaces 15 to 18 which are disposed at 90 to each other. It is seenin FIG. 1 that the indentations or cavities 13 each have a substantiallysquare border at the surface 12 and the border or rim of each cavitysubstantially defines respective legs of the borders or rims of fourcavities adjacent thereto.

Sheet 11 may be made of a number of light transmitting, transparentpolymers including such resins as flexible polyester, polyvinylchloride, polyvinyl fluoride, polyamide, ionomer, acetate or otherresins having high clarity and capable of either being embossed in amanner to define highly polished and reflective surfaces or capable ofbeing metallized to provide a highly reflective surface. For sheetmaterial applicable for use as a highway sign, delineator or reflectivematerial for vehicles, sheet 11 is preferably in the range of 0.002 to0.050 inch thick depending on the particular application andrequirements while the cavity formations 13 preferably vary from 0.0005to 0.025 inch in depth and along a side thereof at the surface 12 of thesheet. In the form of the invention shown in FIGS. 1 and 2, the borderportions 14 of each cavity define narrow ridges at the surface 12 of thesheet perhaps 1 to 2 mills thick or less.

In FIGS. 3 and 4 is shown a modified form of the invention in which asheet 1 1 of reflecting material is emboss-formed with a multitude ofcavities 13 in a major surface 12' of said sheet each cavity beingdefined by three rectangular parallepiped shaped planar surfaces definedby notations l5',16 and 17', said surfaces being disposed at rightangles to each other so as to reflect light rays directed towards orentering each cavity 13"from a plurality of said surfaces whichcooperate to retro-direct or reflex reflect said light rays back in thedirection of the source or along the angle of incidence. Here again, thesurfaces of the walls ',16' and 17' of the cavities 13 may be highlyreflective by virtue of their being extremely smooth finished or acoating 19 of metal applied thereto by plating or metallizing may beprovided on said surfaces to effect retroreflection of said light fromeither major surface of the sheet 1 l In FIG. 5 is shown a modified formof the reflecting device 10 of FIGS. 3 and 4, the features of which mayalso be applied to the device of FIGS. 1 and 2 without departing fromthe invention. The flat rear face 12a of the reflective sheet 11' iscoated with a pressure sensitive adhesive 21 against the-outer surfaceof which is provided a flexible backing sheet 22 serving as a protectionfor the adhesive and a release sheet. The sheet 22 is preferably made ofa silicone coated or treated paper so that it will easily peel off theadhesive when the user is ready to apply the reflective sheeting 10' toa surface such as a sign board. Disposed against the face 12 of sheet11' and preferably sealed thereto is a sheet 20 of transparent flexibleplastic such as one of the polymers described above which sheet servesto protect the face 20' of the sheet 11' from abrasion and to preventdust and moisture from entering the cavities 13 thereof. Thus if ametallized coating 19 is disposed against the surfaces 15' to 17 of thecavity walls of cavities 13', it need not be overcoated with a coatingof transparent plastic since adequate protection thereof may be affordedby the capping sheet 20.

The structure shown in FIG. 5 may also be modified to include materialof the capping layer 20 in the cavities 13' so as to completely fillsaid cavities with the metallized coating 19 disposed either onthesurfaces of the walls l5,16 and 17 of said cavities 13 in the sheet11 or on the surfaces of those portions of the capping material 20abutting the surfaces 15 to 17. The surface 12'a of sheet 1 1' may alsobe utilized as the front face of the reflective device whereupon thecoating 21 of adhesive would either be eliminated or would be disposedon the outer face of the capping layer 20'.

Yet another structure in a retro-reflectorof the type described may behad whereby the metallic coating 19, a metallized layer severalmillionths of an inch thick, may be completely eliminated by filling thecavities 13 or 13' with a resin having an index of refraction which issubstantially different, higher or lower, than the index of refractionof the resin or material comprising the base sheet 11 or 11' so as todelineate or define the interfacial surfaces of the cavity wallssufficiently to effect reflex reflection.

In FIG. 6 is shown reflex reflector 30 comprising a sheet 31 oftransparent material comprising a polymer as described and made of twosheets 32 and 33 which are bonded or welded together after embossingrespective surfaces of said sheets with a plurality of closely spacedindentations 35 and 35, which when the two sheets are properly alignedand joined as shown in FIG. 6 define a plurality of cavities 34 whichare totally enclosed within the sheet 31. The cavities 34 may be ofspherical or cylindrical shape and are formed with highly reflectingsurfaces 34' which serve to refract and reflect light directed againsteither or both the major surfaces 36 and 37 of the sheet 31 back in thedirection of the incident light. In other words, spherical reflectivesurface formations defined by cavities 34 act in the manner of smallspherical glass beads to focus light at or near the spherical surfacewhich reflects and redirects said light thereafter back through thecavity and then the sheet material in the direction of the source.Cylindrical cavity formations 38 shown in FIG. 8 comprising cavities 34"serve to focus light in lines or bands at or near the rear surfaces ofthe cylinders which reflects the band light back through the cavity andthen the sheet in the direction of incident light.

Notation 39 refers to a metallized coating which has been vacuumdeposited against the surfaces of the cavities of only one (33) of theoriginal sheets thereby making said semi-spherical or semi-cylindricalsurfaces highly reflex reflective to light passing through the portionof sheet 31 made from sheet 32 and the noncoated cavity walls thereof.

In FIG. 6 notation 31' refers to the border portions of the two sheets32 and 33 which are sealed or welded together to hermetically seal thecavities 34 formed of the two sheets. The spaces 348 between adjacentcavities shown in FIG. 7 may also be sealed together.

The reflective sheet material 30 of FIGS. 6 to 8 may be fabricated inone manner, by continuously feeding the two sheets 32 and 33 orcontinuously forming same by extrusion of suitable resins such asdescribed above and feeding both sheets simultaneously to respectiveembossing roll pairs operative to provide either the semi-spherical orsemi-cylindrical cavities or channel formations in respective surfacesof the sheets and bringing said embossed surfaces together on acontinuous basis as fed from the respective embossing means with theembossed cavities of each sheet aligned with those of the other sheetupon abutment of the two sheets. The two sheets may be heat sealedtogether by passing same between welding dies in the form of powerrotated rolls compressing cavities together and suitably energized byradio frequency heat sealing energy to electronically weld the surfaces348 between the cavities in both surfaces of the two abutting sheetsdefining single reflecting units as described. One of the two sheets maybe premetallized or may be metallized as described between the embossingoperation and the welding operation. If the sheets are formed withsemicylindrical cavities 34", ridge or band-like formations 34R may beprovided between adjacent parallel cavities or channels which formationsmay be electronically welded together as described.

In FIG. 9 is shown a sheet 40 of reflex reflecting material of the typedefined in the other drawings secured to the convex surface 42 of acurved substrate or base 41. While a flat member made of cornerreflecting members or cavities will retro-reflect light directedthereagainst over an incident angle range of about 90, it is easily seenthat of the flexible retro-reflecting sheet material 40 of the instantinvention is made to conform to a curved surface 42 the angle over whichincident light will be reflected back to the vicinity of the source willbe greatly increased thus greatly enhancing the efficiency of thereflector.

Notations B1 and B2 of FIG. 9 refer to light rays striking thereflective sheet 40 and retro-reflecting at almost 180 due to curvature.If the sheet 40 is relatively thin and made of a flexible plastic, asdescribed, such as a polyvinyl chloride, ionomer or a clear siliconeresin or a rigid plastic such as cellulose acetate butyrate, rigidvinyl, methyl methacrylate, polyamide, polyester or the like which iscapable of flexure in the thickness prescribed herein, it may be made toconform to such articles as posts or telephone poles, curbing, vehiclebumpers and bodies and other convex or concave surfaces and fastenedthereto by means of adhesive, fasteners or clamping means to render thesupport or substrate highly light reflective over a large area thereofif necessary. Because of the high reflection of the corner reflectingcavities provided as described in the sheeting and the fact that largerthan usual areas of reflecting material may be applied when made inaccordance with the teaching of the instant invention and, furthermore,the fact the reflective sheeting is flexible and may be bowed orotherwise made to conform to curved irregularly shaped surfaces, theversatility and efficiency of this type of retroreflector is greatlyincreased.

In the embodiment of the invention shown in FIG. 5 or modificationsthereof employing a plastic filling the corner-reflecting cavities 13',the outer surface of the capping or filling layer 20, which faces thedirection ofincident light and the oncoming vehicle approaching thereflector or sign, may contain transparent or opaque indicia printed,silk screened or otherwise applied thereon and operative to break up thereflected light into patterns or provide images of different colorsacross the face of the reflective sheeting such as lettering oradvertising indicia. The notation A in FIGS. 2,4 and 5 refers to suchindicia which is printed or otherwise applied to the outer surfaces ofthe respective reflecting sheet materials.

In another form of the invention not shown in the drawings, it is notedthat retroreflecting cavity formations such as the corner reflectingcavities l3 and 13 of FIGS. 1 and 3 may be may be of different size andshape in a single sheet to provide either varying reflecting effects orto increase the range of angles or angle over which incident light maybe directed against the sheet and be retro-reflected back to the source.In other words, certain of the cavities may be inclined in onedirection, others in a second direction and still others in a third andfourth directions.

Conventional embossing of glass or plastic materials involves providingsaid materials in a semi-molten or soft condition or the surface stratumthereof to be embossed in said condition and passing said sheet ofsemimolten plastic between at least two rolls, one of which is anembossing roll having its peripheral surface shaped to provide thedesired embossed formations in the surface of the sheet. After theembossing roll has made brief contact with one surface of the sheet, thesheet is removed therefrom onto a powered conveyor, carried away fromthe embossing roll and allowed to solidify whereby little if any controlof shrinkage is effected. It is thus not possible to produce reflectivesheet materials of the types hereinabove described due to the fact thatthe described reflective surfaces of the cavity formations are notprecisely enough formed.

Forming part of the instant invention is an embossing apparatus (notshown) employing a cylindrical embossing roll or drum of substantialdiameter and means for feeding a sheet of material such as a suitablepolymer as described to the surface of the embossing roll and deformingthe surface of said sheet with cavity formations as described whilemaintaining said sheet in abutment with the surface of the drum for asubstantial portion of its rotation such that the sheet or the surfacestratum thereof containing the cavity formations has an opportunity tocool or set with minimum warpage or shrinkage. Maintainance of saidsheet against the surface of the embossing roll or drum for asubstantial portion of the travel thereof, preferably in excess of ofits travel, may be effected by means of a conveyor belt such as a sheetof stainless steel or other material which is power driven in an endlesspath which includes travel of the belt against the sheet abutting thedrum thereby compressing said sheet against the surface of the drum andmaintaining it thereagainst for a substantially portion of the rotationof the drum. In a second machine arrangement, the thin plastic sheet tobe embossed is bonded to a substrate which substrate is guided and drawnor forced against the surface of the embossing drum to force the plasticto be embossed against said surface, by driving said substrate sheetbetween a plurality of powered rollers and said powered embossing rollor drum.

While said sheet is maintained against the embossing roll or drum,portions of said drum or the conveyor belt engaging the sheetthereagainst which are downstream of the entery portion for the sheetare cooled by directing coolant fluid against the inside of the drum,the outside of the conveyor belt maintaining the sheet against the drumor the sheet itself so as to thereby control shrinkage andsolidification or setting of the material of the sheet. Thus thematerial of the sheet being embossed may be dimensionally controlled tothe desired degree and the cavities formed therein to a requisitetolerance as said material is maintained under pressure whilesolidifying or setting.

Iclaim:

1. A reflex reflecting device, comprising; a pair of transparent layersdisposed one against the other, the facing surfaces of each of saidlayers having a multitude of cavities embossed therein, said cavitiesbeing closely spaced and having wall formations of irregular shape whichare highly reflective to light, one of said layers including at leastone cavity aligned with each of the cavities of the other layer todefine a plurality of totally enclosed cavities, the surfaces of saidtotally enclosed cavities being highly reflective and shaped to focuslight directed against the composited laye rs within said totallyenclosed cavities and to reflex reflect the light

1. A reflex reflecting device, comprising; a pair of transparent layersdisposed one against the other, the facing surfaces of each of saidlayers having a multitude of cavities embossed therein, said cavitiesbeing closely spaced and having wall formations of irregular shape whichare highly reflective to light, one of said layers including at leastone cavity aligned with each of the cavities of the other layer todefine a plurality of totally enclosed cavities, the surfaces of saidtotally enclosed cavities being highly reflective and shaped to focuslight directed against the composited layers within said totallyenclosed cavities and to reflex reflect the light back in the incidentdirection.
 2. A device in accordance with claim 1 wherein said totallyenclosed cavities are spherical in shape.
 3. A device in accordance withclaim 1 wherein said totally enclosed cavities are cylindrical in shape.